This question is based on Ahmed Yerima's Attahiru.
Lord Lugard and the British military find it easy to penetrate the Sokoto Caliphate because the

Muslim faithfuls fight with bows and arrows while the British solders use rifles

Emir of Zazzau calls the whitemen to save him from the attack of a fellow Muslim, the Emir of Kontagora

emirates of Sokoto and Zaria have not been friends since the reign of Caliph Abduirahman